Conflicting definition of gettimeofday()

[larskanis]

Ruby declares gettimeofday() on Windows, but the function is also declared in mingw-w64's sys/time.h. Both definitions are incompatible and extension builds fail, if both ruby.h and sys/time.h are included. This is the related error message from rake gem:native of the grpc gem:

compiling ../../../../src/ruby/ext/grpc/rb_byte_buffer.c
In file included from ../../../../src/ruby/ext/grpc/rb_grpc.h:23:0,
                 from ../../../../src/ruby/ext/grpc/rb_byte_buffer.c:27:
/usr/share/mingw-w64/include/sys/time.h:42:13: error: conflicting types for 'gettimeofday'
 int __cdecl gettimeofday(struct timeval *__restrict__,
             ^~~~~~~~~~~~
In file included from /usr/local/rake-compiler/ruby/i686-w64-mingw32/ruby-2.7.0/include/ruby-2.7.0/ruby/defines.h:371:0,
                 from /usr/local/rake-compiler/ruby/i686-w64-mingw32/ruby-2.7.0/include/ruby-2.7.0/ruby/ruby.h:29,
                 from ../../../../src/ruby/ext/grpc/rb_byte_buffer.c:19:
/usr/local/rake-compiler/ruby/i686-w64-mingw32/ruby-2.7.0/include/ruby-2.7.0/ruby/win32.h:318:12: note: previous declaration of 'gettimeofday' was here
 extern int gettimeofday(struct timeval *, struct timezone *);
            ^~~~~~~~~~~~